Carburetor



Feb. 25, 1930` PQ w. ENslGN v .1,748,472

GARBURETOR A Filed April 8. l1332s 4 sheets-sheet z P. w. ENslGN' CARBURETOR Feb. 25, 1930.

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P. W. ENSIGN CARBURETOR 4 Smets-smet 4 Filed April 8, 1926 Patented eb. 25, 1930 v:PAUL W. ENSIGN, -OF LOS ANGELES, CALIFORNIA cannunnmon Application filed April 8,

The general objects of vthe invention may be said to be to provide a carburetor having such a method of operation that the fuel requirements offan internal combustion en l1'. ginelmay be fully satisfied/under all condi- 4 tions of normal running, idling, or sudden acs celeration or deceleration. The manner in which I accomplish these objects,'and further and'more'specific objects, and corresponding 1c accomplishments of the invention, will all be best understood from the following detailed description of a specific, preferred and illustrative form of the invention, reference for this purpose being had to the illustration of a l carburetor in the laccompanying drawings,

in which:

Fig. 1 is a plan partly broken away and in horizontal section, taken as indicated byline 1 1 on Figs. 3 and 4;, and showing a carburetor equipped with my invention in its,

. present preferred form;

Fig. 2 is a side elevation and vertical section taken as indicated by line 2 2 on Fig.- 1;

Fig. 3 is a sectional elevation taken as indicated by line 3 3 on Fig. 1; s

Fig. 4 is a central vertical section taken as indicated by line 4 4 0n Figs. l and 3;

- Fig. 5 is a detailed section taken as indicated by line 5 5 of Fig. 3; Fig. 6is a side elevation partlyin section taken as indicated by line 6 6 on Fig. l; and Figs. 7, 8 and 9 are diagrammatic illustrations showing the various air and fuel passages and illustrating the action of the carburetor under different conditions.

In describing'my invention I shall rst describe the .structure and arrangement ofthe carburetor shown in the drawings and describe how the various passages are, in prac- 40 tice, built into the carburetor structure; and then I shall describe the functions and operations of the various parts.

The carburetor here shown has a main air intake at A, controlled by a choke valve B,

the-details of which need not be herein described. The intake delivers air `into an up- .turning elbow C, and above the elbow C is a Venturi tube D that forms the lower part of main suction passage E in the vupper part of which control throttle Fsisiset in the usual 1926. serial No. 100,489.

manner. Above the throttle thesuction passage connects to the engine intake manifold.- and that part of the passage is, therefore, here called the outlet.

The carburetor is provided with a constant level fuel chamber G, in which fuel is maintained at the constant level L by means of 'float M actuating a valve N, means being provided at'O for depressing the float manually. All the parts so far described are more or less PATENT OFFICE g commonly known and need no detailed description here. Elbow C has a sumpv P at its lowermost point and a suction tube R extends into that sump and connects at its upper end with apassage S which extends upwardly and connects with an idling by-passhereinafter described; the function of the sump and suction tube being t'o pick up any liquid fuel that under certain Circumstances may have gathered in the sump, and to deliver that fuel to the outlet at times when the throttle valve F is nearly closed. This particular provision of a sump and suction tube is, however, a part of the subject matter of application, Serial Number 40,532, carburetor, filed June 30, 1925, by O. I-I.Ensign, and is not, in itself, a subject of the present invention.

Fuel chamber Gr is closed against external atmosphere and arrangements are made so that pressure from intake A is put upon the fuel inchamber G. This is done by a balancing means comprising a tube T presenting its end to the air current in intake A and connecting with an annular passage U which in turn connects with passage V (seel Figs. l and 6),- passage V communicating withfuel chamber G through a nipple W. By this provision the air pressure on the fuelin chamber G is made to depend upon the pressure and velocity at intake A; but this particular provision isa subject matter of Letters Patent No. 1,506,229, issued to 0. H. Ensign on August 26, 1924, entitled Carbu. retor7, and is not, in itself, the subject matter of the present invention.

The carburetor, as here illustrated, comprises three main castings, one of which 1) includes the air inlet, the elbow C, and the suction passage; another (2) comprising mainly the fuel chamber Gand associated parts; and a third (3) that includes control elements, the bore 10 and passage 15 etc. The three castings are joined together at the plane X by suitable bolts or cap screws shown at Y in Fig. 3; and in the plane face of the inixing chamber casting are cast or otherwise formed grooves or depressionsto form, when covered by the joining face of casting 3, several of the passages hereinafter descnbed.

Casting 3 has an upwardlyextending bore, 10 into the lower end of which a fuel riser 11 is screwed', the upper end of the riser having a circular fuel orifice 12 somewhat above the liquid fuel level L. This orifice is adjustable in edective size by the valve 13, which depen-ds from the screw-threaded adjusting head 14. Riser. 11 is, for the greater part of its length, smaller in diameter than bore 10, so that an annular passage is formed around the riser for passing fuel and air downwardly to the horizontal passage 15. The'bore 10 and 'riser 11 form, in effect, an inverted trap over which the fuel is lifted by suction, as will be hereinafter described, the height of the trap being such that the fuel will not flow over it unless suction is applied to the upper end of the riser. At the same time bore 10 forms a suction chamber in which fuel is mixed with air that passes into the chamber from fuel chamber G through a restricted air bleed'er port 16. This restricted air bleeder is formed as a separate screw-threaded bushing. inserted in the casting, the size of its bore being accurately calibrated in order to adapt the carburetor to different motors, and to suit, in proportion, the other co-acting parts of the carburetor. Passage v15 communicates directly with a bore 17, in which fuel nozzle 18 is set, ythis fuel nozzle discharging directly into Venturi tube l); nozzle 18 being set in a plane radial to the Venturi tube and may point upwardly as shown, but not necessarily so. The diagonal angleof the nozzle may be varied to suit dierent motors; and the nozzle may be set horizontally in some cases.

The parts just above described form a fuel passage extending from fuel orifice 12 to the discharge point of `fuel nozzle 18 into the venturi. lt will be noted that, characteris-r tically, this fuelpassage first extends down and then has an intermediate low point or part inthe passage 15, and it is from this low point that fuel is taken off into the accelerating well means hereinafter described.

Fuel nozzle 18 is provided near its dis'- charge end with several small transverse ports 19 communicating with the lower end of an idling by-pass whose upper end communicates with the outlet. In the construction here shown this idling by-pass comprises an annular passage 20 formed in the body of the Venturi tube D; passages 21 and 22, andJ i passage 23, which is formed partly in the face of the mixing chamber casting (as shown 23a is plugged as at 24 and a small port 25 leads out from the upper end of bore 23l into the outlet at a point somewhat above throttle F. The idling by-pass, thus formed, connects between the suction outlet and fuel nozzle of the fuel passage at a point near its discharge into the venturi.

n accelerating well means, comprising the elements about to be described, connects at port 26 with the lower part .of the fuel passage and is provided at its upper end with suction filling means and a limiting means to limit thevheight to which fuel is raised. Briefly described 'in detail, this accelerating well means embodies the following parts. A rather large sized well 27 has a -Ushaped lower end that extends to a point port 26, to the under side of the lowest part of that passage. At its upper end Awell 27 connects by way of a restricted port 28 with a chamberv 29. Chamber 29 has a restricted bleeder port 30 that admits air controllably to the chamber. In this particular case, although not necessarily, bleeder port 30 admitsair from the upper part of fuel chamber G where the pressure is', in this case, lbut not necessarily, controlled by the balancing means before described. Chamber 29 also has a restricted suction port 31 that communicates with passage y32 formed as a bore in the wall of the main suction passage, plugged at its upper end at 33, and having near its upper end a small port 35 extending to the outlet at a point somewhat above the throttle. Bleeder port 30 forms the fuel limiting means for the accelerating well; while suction port 31, etc., form the suction filling means for. the well. Thev position of port 35 with reference to the throttle determines the fuel rise and drop in the accelerating well with relation to throttle opening and closing, as will be hereafter pointed out; and the exact position of port 35 may be determined to suit any given motor.V It may be placed closer to the throttle, as shown at 34 in Figs. 5, 7, 8 and 9;

or, as will be explained, two such ports 34 screw-threaded bushings and their sizes arel accurately calibrated to proportionately suit the other parts of the device and to'obtain the function `and act-ions` hereinafter described. Without limiting the invention', but merely to give a clear idea of proportions that have been found to operate successfully, I may say that port 31 is about .028 inch diameter; port 30 somewhat less .than 5% inch diameter; ports 25,28, 34 and 35 are about 31g' inch diameter; and port 26 about 1/8 inch diameter. These figures are given for a carburetor of about the size shown in the drawings, using gasoline as fuel. The exact sizes of course vary in applying the carburetor to different motors..

It will be' understood that the small port 28 connects between the upper end of the acceleratingwell and the suction chamber 29. This port 28 is smaller than the air -bleed port 30 which admits air to chamber' 29, and is also smaller than the port 26 which connects the lower end of the accelerating well with the fuel passage 15. When the, throttle has been suddenly opened, and creates the differencein pressures, as herein described, and, by that difference of pressures, has drawn the fuel downwardly out of the well and out through the fuel passage, then if the throttle remains wide open air A will subsequently How downwardly through the accelerating well and into themain fuel passage. Naturally, at that time when the same fluid (air) is flowing through all three ports 30, 28 and 246, it is the lsmallest .one of y these three ports which has the .effective controllingV action on the amount of air that will be drawn into the main fuel passage. Of

scribed. For the purposesA of this diagram passages 32, 29 and 27 are illustrated as if they were in the same plane as passages 23, being `illustrated offset in that plane merely for the purpose of simple illustration. And restrlcted port 30 is shown as if itcommu-v nicated directly with the upper part of the fuelchamber G-that is, with an extension port-ion G1 ofthe fuel chamber, which extension portion is shown in the diagrams merely to aid the illustration.4 Idling bypass 23 is illustrated in the diagram as connecting directly to port 19,v without the intervention of the small passages 21 and 22; and in the diagram the showing of separate bushing members has been eliminated, the bushing passages only being shown. All this has been done to simplify the diagram and to facilitate explanation of functionsv and operations.

When the carburetor is in normal operation with throttle valve F somewhat open, the engine running at a uniform speed, the flow of air through venturi D causes'a suction to be exerted on fuel nozzle 18. Thatv 4suction draws` fuel up through riser 11 and also draws air in through :bleeder port 16 into suction chamber 10. Fi 7 indicates the normal operation. The ow of air is shown by dotted linearrows, the passage of fuel by. full line arrows, and the passage of mixed fuel and air by dash line arrows. The mixed fuel and air are drawn through the fuel passage-the annular passage around riser 11 andthen throughpassage 15 and fuel nozzle 18-into vYenturi tube D where `this mixed fuel and air is mixed with air passing upwardly through the venturi. At

the same time air 1s drawn into the fuel passage through the accelerating well, as shown in dotted line arrows.

Now suppose the engine to be idling, with throttle F substantially closed, as shown in Fig. 8. Under these conditions the mainair flowl through venturi D is very small and a much higher suction is, by reason of the throttle closure, put upon port 25 than is put upon the discharge end of nozzle 18. The relatively increased suction on the idling by-pass causes fuel and air to be drawn 'through the fuel passage and from it through ports 19, and to be delivered through port 25` into the outlet. This suction at ports 19 is also sutilcient to cause air to flow from the interior of venturi D into nozzle 18 to ports 19, and thus to mix with the fuell passing through those ports. The suction is also suiiicient to cause at the same time a considerable flow of air through bleeder port v16 into chamber 10 to mix with the fuel that" is being drawn through orifice 12. Thus during the idling' operation there is mixed air Yand fuel flowing to the idling by-pass through'the fuel pas-- sage, and also air from the main suction passage; giving the engine a mixture of proper proportions in the small 'quantity required for idling or near idling operation. The reverse flow of air throughvthe discharge end of nozzle 18 at idling prevents any fuel being discharged into the Venturi tube where it vwould be liable not to be taken up by the slow current of air passing therethrough and therefore would be liable merely to run down the wall of the air intake. The friction of air How through nozzle 18 and through bleeder 16 is sufi-leent, even when the engine is idling, to cause enough depression in chamber -10 to lift the liquid fuel over thenpper end of riser 1v1. The depression necessary, in the design here shown, to lift fuel from float chamber level L through orifice 12 and from horizontal passage 15 to the ports 19 is com` paratively very small, the vertical lifts being small. The depression at port 25, with the throttle closed, is many times greater than that necessary to lift the fuel through 12 and also to 19 and then onA up from ports 19 through port 25. Consequently ports 19 arc made' small as compared with nozzle 18 and bleeder 16.

The idling mixture is adjusted to proper -proportion by regulatingthe degree. of depression applied to the ports 19. This is ac complished by means of the passage 40 which bleeds a1r from the lower or entrance portion of the Venturi tube (from. a point'where the air pressure,when idlin ,is substantially the same as that at the en of fuel nozzle 18) past the controlling valve 42, and through port 43, to the passage S, which passage, as I have before stated, communicates with idling by-p'ass 23. By opening the valve 42 the depression in by-pass 23 and therefore up from thel passage 15.

the suction on ports 19, islessened; and the opposite is the case if valve 42 is closed down. (Passage S is shown diagrammatically in Figs. 7 9; its actual positionand structure are shown in the other figures).

W'hen the engine is idling or running at low speed and power so that itrequires littlefuel and the throttle is closed or near its closed position` th"I suction exerted upon accelerating well 27 by way of port 34 or 35 draws fuel It will be understood that when the engine is idling or working unler small load, and consequently a small amoun'tof fuel is being drawn through the' fuel passage, the zel and air mixture will more or less separate out and a part of the fuel with some air, sinking to the bottom of -passage 15, will accumulate there and in the lower part of the accelerating well. This fuel flowing into the lJ-shaped lower portion restricted port 28, and will continue to rise through 28 until it fills the chamber 29 to the Alevel of the restricted port 31. Upon a very small amount of fuel attempting to pass port 31, it in effect chokes that port, and the suction through 31 is so checked that the air through port 30 then satisfies said suction sufficiently to check further rise of the fuel., Only an extremely minute quantity of fuel will flow through 31 even when the bleeder port 30 is of such a size as to allow any fuel at all to reach 31. rlhe bleederv 30 may be of such-a size (as is sometimes desirable) that no fuel as liquid will be raised through 28. By either means the maximum amount of fuel stored in the accelerating well may be controlled. Any .small amount of fuel which does pass through 31 is part ofthe idling fuel, the major portion of which at all times passes through the idling by-pass. During filling of well 27 some air is being drawn up into the well along with the fuel. rflhis air passes on up through the well, carrying some Ifuel with it through 28and 31, so that the engine will not stop while the well is,filling. This air passage is only temporary, the well quickly accumulating enough fuel to fill it with liquid.

The rate and amount of fuel rise in accelerlating well 27 is governed mainly by the deatin -well with a result that is explained hereinafter. With any given combination of adjustments, port sizes, etc., the amountof depression communicated to the accelerating well depends on the throttle position and engine speed. With the throttle closed or nearly closed, at any engine speed, the depression issulticient to raise fuel quickly to the top of the well.- Generally speaking, the amount of fuel drawn up in the accelerating well depends upon engine speed and throttle position; at higher engine speeds a proportionately smaller closing movement of the throttle will cause fuel to be drawn up in the well, but the difference in action at different engine speeds is slight, due to the peculiar interaction of the depressions communicated to passage.

15 throughI the accelerating Well and the idling by-pass. This is explained hereafter. And at any given engine "speed the height of the fuel level in the well is determined by the amount of throttle closure, with this limitation: that as long as the throttle remains wide enough open to keep the air Howing as indicated in Fig. 7 there is no fuel drawn up 'in the well, but a slight throttle u closure-may merelycause some fuel momenof well 27 is drawn up nto that accelerating well to fill that well a i djto rise through the tarily to drop out of the mixture in passage 15 sind then be gradually picked up by the air flowing through that passage and the air flowing downwardly through the well.

Bythe arrangement of ports 31 and 30 as described, the maximum yheight of fuel in the well is limited and oscillation of the fuel level prevented, and all this is done without discharging solid fuel from the well into the outlet, as would be the case if air bleeder port 30 were omitted. 1f air bleeder .port 30 were omitted, the solid fuel would be drawn on up through passageV 32 and be discharged as liquid through port 34 or 35 into the outlet; andthose ports would then define the limit to which the liqudfuel is raised in the well. But l prefer to limit the fuel height as before described; because the bleeder port 30 not only admits air to pick up fuel to limit the fuel height in the well and carry a little fuel into the suction outlet in admixture with air, but portv30, in conjunction with ort 31, provides an easy and accurate means (by their proportionate sizes) of controllably reducing the amount of effective suction applied to the well and of making thaty suction such that different degrees of throttle opening or closure. causing chan e in the depression applied to port 35, wil cause the fuel to be raised to dierent levels in thel accelerating well.

The full suction on port 35 at lclosed throttle, 1f appliedl unmodified to the accelerating well, would be sufcient to draw li uid fuel right on through 31, 32 and 35.` y modifying the effective suction applied to the top of the well it is not only possible to limit the extreme height of fuel lift to a dimension that can be contained within a practicable carbu- 'retor design, but also to make the control so delicate that different throttlev positions will -cause variations in the small fuel lift.

I have described the operation of the idling by-pass, and also of filling the accelerating well and the means used to-control the operation of each and to limit the maximum amount of fuel that can be lifted into the well. The idling by-pass and well, however, have an interaction due to the fact that the depression applied to the top of the well must lift fuel-not only against gravity but against jthedepression applied to fuel passage 15,

which depression is applied in part through the idling by-pass. That interaction'and its results will n'oW beexplained more fully.

Suppose a condition in which thethrottle has just been closed and the well'is empty. Depression is immediately applied .through the idling by-pass to the fuel passage 15 and' this depressionin the main controls the depressionfor the time being in the fuel pasl sage. At the same time a depression from the same initial'source (above tliethrottle) is applied through the open Well to the fuel passage. rIhe resultant depression in the fuel passage is modified by the air bleed through the nozzle and by the air bleed through 16 near the initial fuel feed orifice 12. But,

regardless of whether the depression applied given amount of bleed (nozzle 18 and bleeder port 16) constantly applied, the depression in the fuel passage must necessarily be lower, when two sections are applied, than when one is applied.

The result is that atV the instant the throttle is closed and the well begins to fill the depression in t-he` fuel passage is somewhat higher than it is later, and therefore more fuel is drawn over at the initial feed orifice 12iminediately after the throttle is closedy than is drawn over later as the well fills'with fuel. The well begins, on throttle closure, to draw off the mixture of fuel and air from the -fuel passage, and the suction through the accelerating well correspondingly and gradually decreases, but continues decreasing until the well has more or less filled up with froth and the charge in the well, cleared of air, has finally' become clear fuel. During all the time the air is bubbling throu h the well, a certain amount of suction, alt ough' decreasingly, is .applied to the fuel passage through the well'in addition'to the suction applied to the fuel passage through the idling Icy-pass. Thus, during the time that Athe well is filling, an additional depression isV applied to the fuel passage to draw over more fuel, more or less injproportion to the increased demand foi` fuel to fillthe well; so that during. the wellfillin period there is suiicient fuel availablebot for well filling and for continued. engine operation. C

During the time that air is thusassing through the well while itis filling, t at air passes on up to the intake above the throttleand carries with it enough fuel to keep the engine running during the time that the well is more or less robbingy the idling by-pass of fuel. In spite of the fact that the increased depression on the fuel passage is drawing over an increased amount of fuel, the filling i of the well might, if the well did not pass on a part of its fuel to the engine intake, rob the idling by-passof enough fuel to more or less interfere with satisfactory engine operation. But the moment the well fills and the liquid clarifies, then all suction through the well to the fuel passage lis stopped; the well is then substantially full and whatever further fuel it 4 draws from the fuel passage is drawn comparatively slowly on account :of the well and the well passages being then 'filled with vclear fuel. Finally the .filling suction passage and fromthat time on the fuel goes from the well to the engine intake and forms a very small l proportion of the idling fuel.

The fact that the fuel at its initial feed into thefuel passage is mixed with air, makes the foregoing described operations possible; that makes it possible for the well, by-pass of air,

during its filling, to apply extra depression,

to the fuel passage to draw fuel over faster than it would otherwise be drawn over, and

. at the same time to have air bubbling through the well during its filling to carry a part of its 4fuel to the engine intake during idling. And these features of operation are found to give an unusually smooth and continuous engine operation throughout periods of uick changes of throttle position, andare t erefore found to lead to unusually high fuel economy. Further itis to be noted, regarding lthe co- -foperafon of the idling by-pass and the accelerating well, that the connection of both of them to the same fuel passage makes the well of the well is limited by the clogging of the action more uniform at varying idling speeds than it otherwise would be. At varying engine speeds, with the saine throttle osition, ,the suction varies very greatly anda xed suction modifying or bleeding arrangement will not; in itself. make uniform the'ei'ective suction applied'to the accelerating well. In my A i desi however, the accelerating well pulls its uel up not only against gravity but against the depression communicated to the fuel passage through the idling by-pass; which depression, originating at the same source as the suction applied to the accelerating well, varies with the effective well suction and thus makes the well action more nearly uniform. The result is that the well fills nearly to the same amount, and at substantially the same speed, at envine idling speeds that may vary as much as fsrom 180 R. P. M. to 750 RFM.

When the throttle is somewhat opened, lessening the depression on the well, the fuel level therein immediately falls; but in falling awa from port 28 it causes port 31 to be freed o the clogging fuel and the effective depression on the well is therefore relatively increased-or, as it might be expressed, maintained`without a sudden drop. Thus a small opening of the throttle does not empty the well, the fuel therein finding a lower level and remaining stationary as long as the throttle position and engine speed remain the'same. The `.fuel dropped out of the well has gone back to the fuelpassage to supply the engine with the eXtra fuel for acceleration; but the fuel4 remaining in the Well is ready for further acceleration. The amount of fuel dropped out of the Well on a partial throttle opening will also depend on the load on the engine. If the engine is'free to speed up quickly the amount of fuel dropped from the well is relatively small; but relatively larger if the engine is loaded and picks up speed slowly. Thus, although the amount of fuel drop from the well depends on both engine loading and the amount and quickness of throttle opening, generally and usually a quick wide opening of the throttle will immediately empty the Welland cause the carburetor then to operate normally as shown in Fig. 7

Fig. 9 shows the condition ensuing on opening of the throttle. The increased suction applied to the fuel nozzle at the4 venturi hasdecreased action of the idling by-pass and has increased the suction on the fuel passage; so that the accelerating well empties both under gravity,'due to air admission at 30-and un der increased suction from the fuel passage.

Ports 25, 34 and 35 are so placed with relation to the throttle as to obtain the actions herein described. With the throttle somewhat more widely open than is shown in Fig.

. 8 it will be seen that the depression above the is throttle position that controls the suction applied to`port 34. With the throttle fully closed the full suction is applied to p ort 34, but with a slight opening movement of the throttle that suction is cut off, and remains cut off throughout further opening movement; whereas the suction on ports 25 and 35 is gradually decreased as the throttle is opened wider and Wider. The combined effect of the two ports 34 and 35 is to place a gradually increasing suction on the accelerating Well as the throttle is closed down, and finally to rather abruptly increase that suction as the throttle goes finally to closed position. And the abruptness of this final increase is the more marked because, until the throttle very nearly reaches closed position,

port 34, being below the throttle, functions as a bleeder to admit air and modify the suction applied to port 35; this bleeding function beingcut off as the throttle passes port 34. Thus in the fully closed position 'of the throttle the accelerating well 27 has an additional depression applied to it that raises the-liquid level high enough to pass up through port 28; while if the throttle is sligh'tly open (in a position above lport 34) the depression transmitted to port 28 is somewhat reduced to allow the liquid level to fall somewhat in the accelerating well 27. And, from what I say regarding the diderent actions of ports 34 and 35, will be, understood the control of accelerating well action that may be had by proper placement of a; single port 35. If that single port is placed relatively high it acts to draw fuel up in the well even though the throttle be quite Widely open, and, conversely, not to drop the fuel completely until the throttle is quite widely open. If placed lower it drops the fuel at a smaller throttle opening.

The restriction at port 28 is made of such size that the size of the bleeder port at 30 may be determined to control thebleeding of pas- -sage 29, and therefore the effective suction placed on the well, without materially varying the rate of air flow through the accelerating well, through port 28, when the well is empty of fuel. The size of passage 26 determines the rate at which the accelerating well will be emptied and therfore the rate at which the excess Lfuel will be delivered into the Venturi tube during acceleration. The restriction at 28 (bleeder port 30 is larger) determines the rate at which air will fiow through the accelerating well in normal operation. The restricted port 28 is, however, made large enough to pass air downwardly as fast or faster than the restricted port 26 can pass fuel into fuel nozzle 18, so that port 26, by its size, controls the rate at which the accelerating fuel is delivered to fuel nozzle 18.

Throughout this description and the following claims I use the term bleed or bleeder to denote the action of a port or 'orifice that admits air to a chamber or paslll used in` the practical art.

sage forthel purpose of relieving or modify-v ing the depression therein. The terms are'so It is, however, to be understood that I do not intend my invention to be limited by speciiic terms or particulars of arrangement and design, which -I-have. heredescribed in full detail in order that those engaged in the art may understand the invention by way of a complete understanding of one typical embodiment. Rather I intend the invention to be limited onlyas expressed in the following claims, whichare` to be read in their broad as well as in their specific meanings.

I claim:

l. Ina carburetor having a constant level fuel supply chamber, an air intake, a main suction passage provided with a throttle, an outlet beyond the throttle, a fuel passage having therein fuel metering means; and communicating with the fuel supply chamber and discharging into the. main suction passage; the combination of an idling by-pass connecting and transmitting suction between the outlet and the fuel passage, and an accelerfuel passage and havin suction filling means communicating with th outlet independently of the idling by-pass. v 2. In a carburetor' havinga constant level fuel supply chamber, an air intake, a. main suction passage provided with a throttle', an outlet beyond the throttle. a fuell passage ating well means conneting at one end to the,

' having therein fuel metering' means; and

communicating with the fuel supply chamber vand discharging into the main suction passage; the combination of an idling by-pass.

connecting and transmitting suction between the fuel passage and the outlet, and an accelerating well means connecting at one end to the fuel passage at a point further removed from the discharge end of the fuel passage than is the point of connection of ,the idling lay-pass, and having suction filling means communicating with the outlet independently of the idling by-pass. l

3. .In a carburetor having a constant level fuel supply chamber, an air intake, a main suction passage provided with a throttle, an-

outlet beyond the throttle, a fuel passage having therein fuel metering means; and communicating with the fuel supply chamber and discharging into the main suction pas-v sage; the'combination of an idling by-pass connecting and transmitting suction between the fuel passage land the outletand an ac- 3 celerating well means connecting atone end idling by-pass and said accelerating well means each h'avinga-n independent controlling air bleed acting to control the effective suction applied to each of the idling by-pass `and acceleratin i well means, respectively,

independently o the other.-

f. 4. In a carburetor having a constant level fuel supply chamber, an air intake, a main suction passage provided with a throttle, an outlet beyond the throttle, a fuel passage communicating with the fuel supply chamber andv discharging into the main suction pasthe accelerating well including a small suction port, a fuel limiting means for the accelerating well comprising an a-ir bleed to said small v suction port, said air bleed being independent Aof the idling by-pass so that suction applied to the accelerating well from theoutlet is independent of suction applied to the idling by-pass, and said air bleed being also independent vof the fuel passage so that suction applied tothe accelerating well is independent of suction applied to the fuel passage.

5. In a carburetor having a constant level fuel supply chamber, an air intake, a main suction passage provided withv a throttle, an outlet beyond the throttle, a flelpassage communicating with the fuel supply chamber and.

discharging. into` the main suction passage, said fuel passage consistlng ofan inverted trap extending above the, fuel level and over which thefuel is raised in metered quantity by suction applied .to the fuel passage, and ofa horizontally extending port-ion leading from the lower end of the inverted trap to the main suction passage, and an air bleed into the inverted trap portion of the fuel iassage above the fuel level ;.the'combination of an idling by-pass and an accelerating well connect-ing lto the horizontal portion of the fuel passage and each having independent suction connection to the outlet and each communicating suction-to the fuel passage.

' ,6. In a carburetor having a constant level fuel supply chamber, an air intake, a main suction passage provided"with a throttle, an outlet beyond the throttle. a fuel passage communicating with the fuel supply chamber and discharging into the main suction passage, said -fuel passage consistingy of an in.-

verted trap' extending above the fuel leveland over which the fuel is raised in metered quantity by suction applied to the fuel passage, andof a horizontally extending portion leading from tlie lower end of the inverted trap to the main vsuction passage, and an air bleed intothe inverted trap portion of the fuel passage above the fuel level; the combination of an idling by-pass and an'accelerating well connecting tothe horizontal portion of the fuel passage and each having independent suction connection to the outlet and each sage near its discharge end andthe accelerating well connecting to the fuel passage at the under side of the horizontal portion and at a point between the inverted trap and the point of connection of the by-pass.

7. In a carburetor having a constant level fuel supply chamber, an air intake, a main suction passage provided with a throttle, an outlet beyond the throttle, a fuel passage communicating with the fuel supply chamber and discharging into the main suction passage, said fuel passage consisting of an inverted trap extending. above the fuel level and over which the fuel is raised in metered quantity by suction applied to the fuel passage, and of a horizontally extending portion leading from the lower end of the inverted trap to the main suction passage, and an air bleed into the inverted trap portion of the fuel passage above the fuel level; the combination of an accelerating well supplied with fuel from the bottom of the horizontal portion of the fuel passage, said accelerating well being provided with suction filling 'means communicating with the outlet and also with air bleed controllingmeans independent of the fuel passage and its air bleed.

8. In a carburetor having a constant level fuel supply chamber, an air intakepa main suction passage .provided with a throttle, an outlet beyond the throttle, a fuel passage communicating with the fuel supply chamber and discharging into the main suction passage, said fuel passage consisting of an inverted trap extending above the fuel level and over which the fuel is raised in metered quantity by suction applied to the fuel passage., and of a horizontally extending portion leading from the lower end of the inverted trap to the main suction passage, and an, air bleed into the inverted trap portion of the fuel passage above the fuel level; the combination of an accelerating well connecting with the bottom of the lowermost portion of the fuel passage and provided with suction filling means connecting to the outlet, the connection of the accelerating well to the fuel passage being in the form of a'U leading downwardly from `the fuel passage and then upwardly into the accelerating well.

9. In a carburetor having a constant level fuel supply chamber.v an air intake, a main suction passage rovided with a throttle, an outlet beyond the throttle, a fuel passage communicating with the fuel supply chamber and discharging into the main suction passage ;-the combination of an accelerating well means restrictedly connected at its lower end with the llowermost point in the fuel passage and having at its upper end a restricted port and a suction chamber into 'which said port opens, suction filling means connected to said chamber through a restricted suction port and connecting with the outlet, an air bleed port also communicating with said chamber, the restricted |connection at the lower end of the accelerating well forming a means of controllin the rate of liquid flow from the well to the uel passage, and the restricted port at the upper end of the accelerating well being smaller` than the air bleed port and than the restricted connection between the well and the fuel passageand forming a means of controlling t-he How of air through the accelerating well to said fuel passage when the accelerating well is empty of liquid.

10. In a carburetor, a`fue1 supply chamber, an air intake, a main suction passage provided with a throttle, an outlet beyond the throttle, a fuel passage leading from the fuel supply chamber and comprising an inverted trap and a horizontal portion leading from the lower end of the trap and discharging into the main suction passage, an idling bypass and an accelerating well connecting directly with the horizontal portion of the fuel passage and each communicating with the outlet beyond the throttle, whereby suction from the outlet is applied independently tov the by-pass and well and each communicates I suction to the fuel passage.

11'. In a carburetor, a fuel supply chamber, an air intake, a main suction passage provided with a throttle, an outlet beyond the throttle, a fuel passage leading from the fuel supply chamber and comprising an .inverted air bled trap and a horizontal portion leadlng from the lower end of the trap and discharging into the main suction passage, anpidling by-pass andl an acceleratingwell connecting directly with the horizontal portion of the fuel passage and each communicating with the outlet beyond the throttle, whereby suction from the outlet lis vapplied independently to the bv-pass and well and eachv commu- 'to bleed air controllably intol the by-pass and well independently of each other, so thatthe effective suction applied to the by-pass and well are independently controllable.

12. In a carburetor, a fuel supply chamber, an air intake, a main suction passage provided with a throttle, an outlet beyond the throttle, a fuel passage leading from the fuel supply chamber and comprising an inverted trap anda horizontal portion leading from the lower end of the trap and discharging into the main suction passage, an idling bypass and an accelerating well connecting directly with the horizontal portion of the fuel passage and each communicating with the outlet beyond the throttle, whereby suction from the outlet is applied independently to the by-passand well and each communicates suction to the fuel passage, thelower end of the accelerating well bein U-shaped and connecting into the lower si e of the horizontal portion of the fuel passage. Y

13. In a carburetor, a fuell supply chamber, an air intake, a main suctlon passage provided with a throttle, an outlet verted air led trap and a horlzontal portion leading from the lower end of the trap and discharging into the mainsuction passsge, an idling by-pass and anaccelerating we necting directly with the horizontal portion of the fuel passage and each commumcating with the outlet beyond the throttle, whereby suction from the outlet is applied'independently to the by-pass and well and each communicates suction to the fuel passage, and

means to bleed air controllably into the by-l pass and well vindependently of each other,

v so that the effective suction applied to the by-pass and well are independently control- A lable, the lower end of the accelerating well being U-shaped and connecting into the lower side ofthe horizontal portion of the fuel passage.

- In witness that I claim the foregoing I have f hereunto subscribed' my name this 26th day of March 1926.

PAUL W. ENSIGN.

eyond the throttle, a fuel passa e leading` from the yfuel suppl chamber an com prislng an in- 

